DESCRIPTION (Taken from application) Obesity is one of the major public health problems in the USA. Of all the adverse lifestyle factors thought to increase the risk of high levels of body fat, low physical activity and a high dietary fat content are thought to be especially important. However, the relative importance of these two factors is not known. We propose a new study in the PR China to address this important issue. Previous studies in China have demonstrated that a wide range of physical activity exists in individuals with both high and low dietary fat intakes, thus permitting a comparison of their separate effects on body fat. Two hypotheses will be tested in a cross-sectional study of 112 healthy adult men and women aged 37-47 years: i) physical activity, but not dietary fat intake (expressed as a percent of metabolizable energy), is a significant predictor of individual variability in total body fat; ii) the proportion of body fat located centrally is negatively associated with physical activity and not significantly associated with dietary fat intake. Subjects for the study will be from sedentary urban groups and physically active rural groups and within each location individuals living in both high and low per capita income households (shown to reflect fat intake) will be recruited. Body fat and fat distribution will be determined by isotope dilution and anthropometry, dietary intake by a 7-day food record, and physical activity by activity monitors; additional variables for characterization of the subject population will also be determined. Multi-factor analysis of variance and covariance will be used to determine the separate effects of physical activity and diet composition, taking into account potential confounding variables. We anticipate that the results of this study will further our knowledge of the underlying causes of excess body fat during adult life, and will provide knowledge that will help to optimize recommendations for prevention and treatment of adult overweight and obesity.